213Cases With Male Isolated Gonadotropin-releasing Hormone Deficiency:Clinical Feature Analysis And Gene Mutation Study

Objective:Isolated gonadotropin-releasing hormone （GnRH） deficiency （IGD） is a genetic disorder caused by defects in the secretion of GnRH or its action and has a broad spectrum of human reproductive disorders which varies from congenital isolated hypogonadotropic hypogonadism （IHH） to adult-onset isolated hypogonadotropic hypogonadism （AHH） in males. In the presence of anosmia or hyposmia, IHH is defined as Kallmann syndrome （KS）, whereas in the presence of a normal sense of smell, it is termed normosmic IHH （nIHH）. In this study, we were aimed to describe the clinical features of213Chinese males with IGD, reveal the genetic cause of some of the IGD cases, analyze their genotype phenotype correlations, and report the treatment outcomes in some of these cases.Methods:We collected the male IGD patients in the outpatient and filed their medical and family history. The physical examinations, laboratory and imaging studies were performed. The PCR and agarose gel electrophoresis, whole genome chip analysis and semiconductor target areas sequencing were used to reveal the molecular defects of two KS and ichthyosis brothers. We also used semiconductor target areas sequencing and Sanger sequencing to detect the mutaitons in15IHH genes in4KS patients with cleft lip/palate （CLP） and8IGD patients （including5paitents with KS, one patient with nIHH and two patients with AIHH） without CLP. Functional prediction and conservation analysis were performed to predict the consequence of the detected mutations. The patients were treated with gonadotropin and followed up to observe the treatment outcomes.Results:The reproductive phenotypes in the IHH patients included gynecomastia （23/211）, microphallus （42/211）, cryptorchidism （21/211）, scrotum dysplasia （3/211）. These reproductive phenotypes presented either in KS or nIHH patients. We also found one nIHH males with unilateral testicular agenesis （1/211）. The non-reproductive phenotypes in our patients contained ichthyosis （3/211）, unilateral renal agenesis （2/211）, cleft lip （2/211）, cleft lip and dental agenesis （1/211）, cleft lip and palate combined with dental agenesis and high arched palate （1/211）, nystagmus and iris hypoplasia （1/211）. These non-reproductive phenotypes only presented in KS patients. The results of karyotype analysis showed that15out of the211IHH patients （7.1%） had polymorphic chromosomal variants. The phenotypes of the two Chinese brothers with KS and X-linked ichthyosis were characterised by bilateral cryptorchidism, unilateral renal agenesis in one patient but normal kidney development in another. Genetic study showed that the two affected siblings had the same novel deletion at Xp22.3including exons9-14of KALI gene and entire STS gene. We also identified two novel heterozygous missense mutations in FGFR1,（NM₀01174066）:c.776G>A （p.G259E） and （NM₀01174066）:C.358C>T （p.R120C）, in a23-yr-old KS male with cleft lip and an18-yr-old KS patient with cleft lip and palate, dental agenesis and high arched palate, respectively. By the way, one heterozygous missense mutation in KISS1R,（NM032551）:c.587C>A （p.P196H）, which was reported previously, was identified in an18-yr-old KS male with cleft lip and dental agenesis. All the mutations were not presented in any of the200unrelated normal controls. However, we proved the KISS1R C.587C>A mutation was presented in the father and grandfather of the patient. These patients were treated with gonadotrophin and followed up for at least2years. The results showed that the four patients with KALI or FGFR1mutaitons failed to achive spermatogenesis after treatment.Conclusion:In this study, we found several reproductive and non-reproductive phenotypes in Chinese males with IGD. We also identified some novel mutations of IGD causal genes in some of these patients, which may facilitate the genetic diagnosis and counselling for IGD. The failure to induce spermatogenesis in our patients with deletion in KALI or mutations in FGFR1gene provided further support for the assuption that KALI and FGFR1mutations affect gametogenesis directly within the gonads and offered us a new understanding for the mechanism of male infertility.